Characteristics variations of size-fractionated anammox granules and identification of the potential effects on these evolutions

Ruili Yang; Yenan Li; Jinglin Chen; Junbin Wu; Shici Zhang; Shaohua Chen; Xiaojun Wang

doi:10.1016/j.envres.2023.116875

Characteristics variations of size-fractionated anammox granules and identification of the potential effects on these evolutions

Environ Res. 2023 Nov 15;237(Pt 2):116875. doi: 10.1016/j.envres.2023.116875. Epub 2023 Aug 26.

Authors

Ruili Yang¹, Yenan Li², Jinglin Chen³, Junbin Wu³, Shici Zhang⁴, Shaohua Chen³, Xiaojun Wang⁵

Affiliations

¹ CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Fujian, Xiamen, 361021, PR China; Yancheng Institute of Technology, Jiangsu, Yancheng, 224051, PR China.
² CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Fujian, Xiamen, 361021, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China.
³ CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Fujian, Xiamen, 361021, PR China.
⁴ Hubei Geological Survey, Wuhan, 430034, PR China.
⁵ CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Fujian, Xiamen, 361021, PR China. Electronic address: xjwang@iue.ac.cn.

PMID: 37640093
DOI: 10.1016/j.envres.2023.116875

Abstract

Anaerobic ammonium oxidation (anammox) granulation which contributed to system stabilization and performance improvement has great potential in the field of wastewater nitrogen removal. The researchers fractionated anammox granules into small-size (0.5-0.9 mm), medium-size (1.8-2.2 mm), and large-size (2.8-3.5 mm) categories to examine their properties and mechanisms. Various analyses, including high-throughput sequencing, determination of inorganic elements and extracellular polymeric substances (EPS), and microbial function prediction, were conducted to characterize these granules and understand their impact. The results revealed distinct characteristics among the different-sized granules. Medium-size granules exhibited the highest sphericity, EPS content, and anammox abundance. In contrast, large-size granules had the highest specific surface area, heme c content, specific anammox activity, biodiversity, and abundance of filamentous bacteria. Furthermore, the precipitates within the granules were identified as CaCO₃ and MgCO₃, with the highest inorganic element content found in the large-size granules. Microbial community and function annotation also varied with granule size. Based on systematic analysis, the researchers concluded that cell growth, chemical precipitation, EPS secretion, and interspecies interaction all played a role in granulation. Small-size granules were primarily formed through cell growth and biofilm formation. As granule size increased, EPS secretion and chemical precipitation became more influential in the granulation process. In the large-size granules, chemical precipitation and interspecies interaction, including synergistic effects with nitrifying, denitrifying, and filamentous bacteria, as well as metabolic cross-feeding, played significant roles in aggregation. This interplay ultimately contributed to higher anammox activity in the large-size granules. By fully understanding the mechanisms involved in granulation, this study provides valuable insights for the acclimation of anammox granules with optimal sizes under different operational conditions.

Keywords: Granulation mechanism; Microbial function; PICRUSt2; Physicochemical characteristics; Size-fractionated anammox granules.